Powered roller mechanism

ABSTRACT

A powered roller movable laterally of its axis between a retracted position and an advanced position is unitary with the ring gear of an eccentric planetary gear set having a sun gear input. The ring gear is journalled on the planet gear carrier eccentrically thereof for movement thereby along an orbit between the two positions of the roller.

United States Patent 1 1 3,721,130 McKee 5]March 20, 1973 [54] POWERED ROLLER MECHANISM [56] References Cited [75] Inventor: James E. McKee, Goleta, Calif. UNITE D STATES PATENTS [73] Assignee: Republic National Bank of Dallas, 1,740,792 12/1929 Strachaner et a] ..74/86 UX Irving Trust Company and Union 2,574,376 1 1/1951 ChildS et al ..74/86 X Bank 7 Primary Examiner-Milton Kaufman [22] Fled: 1970 Attorney-Smyth, Roston & Pavitt 21 A l. N .2 96 718 l 1 pp 57 ABSTRACT Related Apphcamm Data A powered roller movable laterally of its axis between [62] Division f Ser No, 865,071, Oct 9, 1959, ahaa retracted position and an advanced position is unitadoned. ry with the ring gear of an eccentric planetary gear set having a sun gear input. The ring gear is journalled on 52] U S Cl 74/86 the planet gear carrier eccentrically thereof for move- [51] In} .Cl 1/44 mam thereby along an orbit between the two positions 58 Field of Search ..74/86 the 19 Claims, 16 Drawing Figures PATENTEUHARZU I975 SHEET 1 OF 5 Wax r019.

PATENTEUMARZO I973 SHEET H 0F 5 POWERED ROLLER MECHANISM CROSS-REFERENCES TO RELATED APPLICATIONS This is a division of application Ser. No. 865,071, filed Oct. 9, l969, abandoned.

BACKGROUND OF THE INVENTION For a number of widely different purposes it is useful to rotate a rotary body and to shift the rotary body on a path transversely of its axis from a retracted position to one or more advanced positions. For example, the rotary body may be a grinding wheel which is advanced towards a workpiece that is to be processed.

The invention has special utility in the form of a powered roller that is normally retracted below a support plane and, when desired, is advanced upward for tangential contact with the bottom surfaces of objects to move the objects along the support plane. The initial embodiment of the invention is employed in this manner to shift heavy cargo items along the cargo space of a vehicle such as a jet aircraft. The description herein of this initial embodiment will provide adequate guidance for persons skilled in the art who may have occasion to apply the underlying concept of the invention to other specific purposes.

The cargo space of an airplane is commonly provided with built-in freely rotatable support elements in the form of balls and rollers which define a support plane for palletized or containerized cargo items and which minimize frictional resistance to movement of the cargo items along the support plane. For the purpose of illustration, the invention will be described as applied to such built-in structure of the character disclosed in the Davidson U.S. Pat. No. 3,262,588 issued July 26, 1966, which prior disclosure is hereby incorporated into the present disclosure by reference.

In the Davidson disclosure, the floor of the cargo space that is opposite the side door of the aircraft is provided with ball mat, the universally rotatable balls of which define a support plane and serve to minimize frictional resistance to movement of cargo items from the doorway onto the door mat as well as to minimize frictional resistance to direction change of the cargo items and initial movement of the cargo items longitudinally of the aircraft. The areas of the floor space that extend in both longitudinal directions from the ball mat are provided with rotatable support elements in the form of rollers having their axis perpendicular to the longitudinal axis of the aircraft, the rollers being mounted on so-called trays that are releasably anchored to seat rails in longitudinal alignment with the aircraft.

The described arrangement of ball mats and roller trays greatly facilitates stowing cargo units in the aircraft but nevertheless physical effort and appreciable time is required to push a cargo item from the region of the side door to the central area of the ball mat and then to transfer the cargo unit to the roller trays for movement longitudinally of the aircraft. Usually at least five men are required to load or unload a large cargo aircraft in 30 to 40 minutes and, based on an average load per aircraft today of 58,000 pounds, only eleven planes a day can be loaded or unloaded by a cargo-handling crew. It is also to be noted that serious manual operation.

With the era approaching of jet aircraft such as the Boeing 747 and the Lockheed L-lOll of greatly increased cargo capacity and correspondingly increased fixed costs, concerted efforts are now being made to meet the need for more nearly automated cargo handling methods involving powered means incorporated in the structure of the cargo space to move cargo items under more or less remote control. A primary object of the present invention is to meet the various problems involved in satisfying this need and thus make it possible for one man, or at most two men, to load 100,000 pounds of cargo or more into a large aircraft in twenty minutes or less.

It has been determined that the new requirements may be met by providing the cargo space of the aircraft with suitably constructed reversible powered rollers to cooperate both with the universally rotatable balls of the ball mats and with the rollers of the longitudinal roller trays, provided that the powered rollers are shiftable by remote control from retracted positions out of the way below the support plane of the cargo space to upper positions at which the powered rollers protrude above the support plane for tangential traction contact with the bottom surfaces of the cargo items.

For example, a pair of reversible retractable power rollers with their axis parallel with the aircraft axis may propel cargo items from the region of the side door a desired distance across the ball mat where a powered roller with its axis perpendicular to the longitudinal axis of the aircraft may take over to initiate movement of the cargo items in either direction longitudinally of the aircraft away from the entrance area. A third powered roller of the same orientation as the second powered roller may complete the longitudinal travel of cargo items from the ball mat into the short bay forward of the side door and successive similarly oriented powered rollers may successively engage cargo items to propel the items longitudinally of the aircraft any required distance towards the rear end of the cargo space.

The specific objects of the presently preferred embodiment of the invention include the following: to provide a reversible powered roller unit that is compact enough to fit into the shallow space between the cargo support plane and the floor of the aircraft and yet is powerful enough to propel a cargo item weighing up to 13,500 or more pounds at a rate, for example of 60 feet per minute; to make such a powered roller unit substantially immune to impact damage by portions of cargo items that may sag below the support plane; to provide sufficient power to move the heaviest cargo item and at the same time safeguard the powered roller mechanism from damaging stress in the event that movement of the cargo item is abruptly blocked while the roller is energized; to provide efiicient means to raise and lower the powered roller under remote control with minimal addition of structure required to raise and lower the roller and without complicating the remote control only one signal being required both to cause energization and raising of the roller or to cause deenergization and lowering of the roller; to safeguard cargo handlers by making it unnecessary for a handler to precede a moving cargo item or even to be immediately adjacent a cargo item when a powered roller is energized to propel the cargo item.

SUMMARY OF THE INVENTION As will be explained more fully, the invention takes advantage of the unique and highly advantageous geometrical behavior of what may be termed an eccentric planetary gear train comprising: an input'sun gear; a planet gear carrier with its axis of rotation concentric to the sun gear; a ring gear mounted on the carrier eccentrically thereof, i.e., with its axis of rotation offset from the common axis of rotation of the carrier and sun gear; and a planet gear joumalled on the carrier in mesh with both the sun gear ad the ring gear. Such a planetary gear train may be adapted to the purpose of the present invention by simply making the cargopropelling roller unitary with the ring gear. Preferably the ring gear is a cylindrical member of substantially approximately the same axial dimension as the propelling roller with the propelling roller encasing the ring gear and with the carrier axially elongated to extend beyond both ends of the cylindrical ring gear for effective support of the propelling roller.

A basic advantage of such an arrangement is that rotation of the planet gear carrier moves the propelling roller in an orbit between a retracted position below the cargo support plane and an upper position protruding sufficiently above the support plane for effective traction contact against the bottom surface of a cargo unit. With the planet gear cooperative with the sun gear effective to reversibly rotate the propelling roller on its axis at any orbital position of the propelling roller, the only further actuation requirements are rotation of the carrier to raise and lower the propelling roller and releasable immobilization of the carrier at the elevated position of the propelling roller.

Within the scope of the invention various means may be provided to rotate and releasably immobilize the carrier. For example a second power input in addition to the sun gear may be provided to rotate the carrier directly under remote control. A feature of the preferred practice of the invention, however, is the concept of using the sun gear as the sole power input and of diverting at least a portion of the power flow temporarily to rotate the carrier when required for raising and lowering the propelling roller. In this regard an important feature of the present embodiment of the invention is the further concept of frictionally coupling the planet gear carrier and the ring gear to provide the required diversion of the power flow.

The friction coupling causes rotation of the planet gear carrier whenever energization of the sun gear is initiated in either rotary direction and the invention provides a first latch to immobilize the carrier automatically when the cargo-propelling roller rises to its effective upper position. Subsequent deenergization of the latch to unlatch the carrier to permit the sun gear to rotate the carrier to lower the cargo-propelling roller to its retracted position whereupon a second latch automatically immobilizes the carrier to keep the roller retracted.

In the preferred embodiment of the invention this automatic dual latch concept is carried out by forming the carrier with a surface concentric to its axis of rotation with a suitable latch recess therein that is engaged by the first latch when the propelling roller is elevated and is engaged by the second latch when 180 rotation of the carrier retracts the propeller roller. With the first latch spring biased away from the carrier and the second latch spring biased towards the carrier, suitable electromagnetic means responsive to energization of the sun gear is employed to overcome reversing the bias of both latches. Energization of the electromagnetic means causes the second latch to retract from the latch recess to release the planet gear carrier for upward movement of the propelling roller and also causes the first latch to seek the latch recess to stop the carrier when the propelling roller reaches its upper position. In the present embodiment of the invention both latches are carried by a reciprocative yoke which is spring biased in one direction and is operable by solenoid means in the opposite direction.

Other features of the invention include: the incorporation of a motor in the powered roller unit to energize the sun gear; the further incorporation of reduction gearing of the planetary type; the combination with the planetary reduction gearing of torque limiter means; the provision of a switch mechanically operated by a solenoid-actuated latch for the planet gear carrier, which switch energizes the motor whenever the latch releases the carrier at the lower retracted position of the cargo-propelling rollers the provision of a control switch with a push button to energize the latch solenoid as long as the push button is depressed with the further provision of delay means to prolong the energization of the motor for a predetermined number of seconds after the push button is released; the provision of simple friction means to couple the carrier and ring gear; and the shaping of the housing of the powered roller item with inclined marginal surfaces to minimize input damage to the item by sagging portions of cargo items.

The various features and advantages of the invention may be understood by reference to the following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to be regarded as merely illustrative:

FIG. 1 is a diagrammatic view to explain the geometrical behavior of what may be termed an eccentric planetary gear train that is a basic feature of the invention;

FIG. 2 is a diagram showing a cargo-propelling roller encasing the ring gear and showing two latches controlled by a solenoid and a cooperating spring, the mechanism being shown at the normal lower position of the cargo-propelling roller with the solenoid deenergized;

FIG. 3 is a view similar to FIG. 2 with the powered roller at its upper position to propel a cargo item, the solenoid being energized;

FIG. 4 is a view similar to FIG. 3 showing the solenoid deenergized to permit the cargo-propelling roller to return to its normal lower position;

FIG. 4a is a diagrammatic view of a modification wherein retarding means acting externally on the roller causes the roller to be elevated when the sun gear is energized;

FIG. 5 is a plan view of the presently preferred embodiment of the invention with parts broken away;

FIG. 6 is a longitudinal sectional view of a longitudinal portion of the structure shown in FIG. 5;

FIG. 7 is a longitudinal sectional view on a different plane showing the rest of the structure;

FIG. 8 is a plan view of the latch yoke;

FIG. 9 is a side elevational view of the yoke;

FIG. 10 is an end elevation on reduced scale of the structure shown in FIG. 5;

FIG. 10a is a fragmentary view in side elevation of an alternate form of a torque limiter that may be employed;

FIG. 11 is a fragmentary diagrammatic plan view of the cargo space of an aircraft;

FIG. 12 is a wiring diagram of a control circuit for a propeller roller unit;

FIG. 13 is a diagrammatic side elevational view illustrating how the principles of the invention may be embodied in means to drive and shift a grinding wheel; and

FIG. 14 is a view taken along the line 14 M of FIG. 13 showing means to indicate the advance of the grinding wheel.

DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION Basic Mode of Operation FIG. 1 shows what may be termed an eccentric planetary gear train that is a basic feature of the invention. The gear train includes an input sun gear 20, a planet gear carrier 22 with its axis of rotation concentric to the sun gear, a ring gear 24 and a planet gear 25 that is in mesh both with the sun gear and the ring gear. The planetary gear train is eccentric in the sense that the ring gear 24 is journalled on the planet gear carrier 22 for rotation on an eccentric axis 26, the axis 26 being offset from the common axis of rotation 28 of the sun gear and planet gear carrier. It is apparent that rotation of the carrier 22 on the axis 28 moves the axis 26 of the ring gear in a circuit orbit. In FIG. I the ring gear is at the top of its orbit with its axis 26 at the point designated 26. When the ring gear is at its opposite position at the bottom of its orbit its axis is at the point designated 30 in FIG. 1.

If the carrier 22 is immobilized by any given orbital position of the ring gear 24, power flows from the input sun gear through the planet gear 25 to the ring gear to rotate the ring gear about its axis. If the planetary gear train is locked by means acting between two components thereof, the ring gear 24 will not rotate on its axis 26 but will move bodily along its circular orbit. Thus power from the sun gear may flow to the ring gear alone to cause rotation of the ring gear at whatever degree of elevation the ring gear may be or the power flow may be diverted to the carrier 22 whenever it is desired to change the elevation of the ring gear. It is to be understood, however, that within the scope of the invention instead of diverting power flow from the sun gear to the carrier 22 to raise and lower the ring gear, a second power input may be applied directly to the carrier to raise and lower the ring gear.

FIG. 2 shows how the underlying concept of an eccentric planetary gear train is incorporated in the presently preferred embodiment of the invention. In the construction represented by FIG. 2, the ring gear 24 is an elongated cylinder and a cargo-moving roller, generally designated 32, is in the form of a cylinder that fixedly encases the ring gear cylinder. The roller may be equipped with a suitable coating 34 of plastic, for

example polyurethane, for frictional contact with the cargo. The carrier 22 is of circular peripheral configuration with a single latch recess 35 for cooperation alternately with a first latch 36 and a second latch 38, the two latches being unitary parts of a reciprocative yoke 40. In FIG. 2 the roller 3 is in its normal position at the bottom of its orbit and the yoke 40 is in its normal position biased to the right by a spring 42 to bias the first latch 36 away from the carrier 22 and to hold the second latch 36 in engagement with the latch recess 35 to immobilize the carrier but the bias of the yoke may be reversed by a solenoid 44.

In the preferred embodiment of the invention, rotation of the carrier 22 to raise and lower the roller 32 is accomplished by frictionally coupling two components of the planetary gearing. For this purpose the double arrow 45 in FIGS. 2 4 represents frictional means effective between the ring gear 24 and the carrier 22 to yieldingly lock up the planetary gear train for rotation as a unit, the friction means acting specifically between the roller 32 and the carrier.

In the preferred practice of the invention the solenoid 44 is energized in time relation to energization of the motor that drives the sun gear 20 and for this purpose, the motor is controlled by a switch 46 shown in FIGS. 2 4 which is responsive to the shifting of the latch yoke 46. The switch 46 is normally closed and is in its normally closed state in FIG. 2. The latch yoke 40 is shown in solid lines at its right limit position in FIG. 2 and the dotted lines in FIG. 2 indicate an intermediate position of the switch at which the latch 36 presses against the periphery of the carrier 22, the latch recess 35 being remote from the latch 36. FIG. 4 shows the latch yoke at another intermediate position at which the solenoid 44 is deenergized and the spring 42 urges the latch 33 against the arcuate periphery of the carrier 22. FIG. 3 shows the roller 32 at its upper position with the latch yoke at its left limit position. The switch 46 that controls the motor is open in FIG. 2, where the latch yoke is at its right limit position. At all other positions of the latch yoke, including the intermediate position indicated by dotted lines in FIG. 2 and the intermediate position shown in FIG. 4, the switch 46 is closed to energize the motor. Thus the switch 46 is closed at all positions of the latch yoke 40 except the right limit position shown in FIG. 2.

The operating cycle is as follows: Starting with the parts in their normal positions shown in FIG. 2, the motor and the solenoid being deenergized and the cargo-propelling roller 32 being at its normal lower retracted position, the latch 38 is in engagement with the latch recess 35 to immobilize the carrier 22 and the latch 36 is retracted. When the solenoid 44 is energized by a control signal the latch yoke 40 is shifted leftward from its normal position to an intermediate position indicated by dotted lines in FIG. 2 where the latch 36 presses against the arcuate periphery of the carrier 22. This initial leftward shift of the latch yoke 40 closes the switch 46 to actuate the sun gear 20, whereupon the carrier 22 rotates by virtue of the frictional coupling of the carrier and the ring gear. With the solenoid pulling the latch 36 against the periphery of the carrier 22, the latch 36 snaps into engagement with the latch recess 35 at the end of the 180 of rotation of the carrier to immobilize the carrier as shown in FIG. 3

with the cargo-propelling roller 32 at its elevated position. In effect, the frictional coupling between the ring gear and the carrier locks up the planetary gear train to carry out the 180 of rotation of the carrier.

When the control signal is subsequently removed with the parts in the positions shown in FIG. 3, the latch yoke 40 is shifted rightward by the spring 42 to cause the latch 36 to release the carrier 22 and to cause the latch 38 to press against the periphery of the carrier as shown in FIG. 4. Switch 46 remains closed for continued energization of the motor until another 180 of rotation of the carrier 22 is completed to permit the latch 38 to seat again in the latch recess 35 to immobilize the carrier 22 with the cargo-propelling roller at its normal retracted position. The final shift of the latch yoke 40 rightward from the position shown in FIG. 4 to the normal position shown in FIG. 2 opens the switch 46 to deenergize the motor with the cargo-propelling roller 32 at its lower retracted position.

If the ring gear 24 with the roller 32 fixedly mounted thereon is held against rotation while the sun gear is energized, the carrier 22 will rotate to move the nonrotating roller in a rotary path. It is apparent, therefore, that instead of frictionally coupling the carrier and the ring gear to change the elevation of the roller 32, simple frictional brake means may be applied directly to the roller.

FIG. 4a shows how such a brake means in the form of a leaf spring 47 may be mounted below the roller 32 to exert upward pressure against the underside of the roller when the roller is at its lower retracted position. The range of resilient flexure of the leaf spring 46 is sufficient to follow the upward movement of the roller from its retracted position until the roller makes initial frictional contact with a cargo item whereupon the cargo item takes over the function of retarding the roller. The roller 32 then completes its upward movement to its upper limit position to lift the cargo item and, preferably, in doing so moves out of the range of the leaf spring. If desired, an equivalent of the leaf spring may be employed in the form of a resilient body of elastomeric material, such as a suitable foamed plastic.

Structural Details of the Preferred Embodiment Turning now to the specific structure of the presently preferred embodiment of the invention and referring first to FIGS. 6 and 7, a motor, generally designated 50, has a shaft 52 which is journalled in bearings 54 and, by means which will be described later, the shaft is operatively connected to a first spur gear 55 near the right end of FIG. 6. The first spur gear 55 in turn meshes with a second gear 56 shown near the left end of FIG. 7 which is keyed to a shaft 58 that is joumalled in bearings 60. The shaft 58 carries an axially elongated previously mentioned sun gear 20 inside the cargopropelling roller 32.

Rotatably mounted on the sun gear shaft 58 by bearings 62 is the previously mentioned planet gear carrier 22 which is axially elongated and carries a pair of coaxial planet gears which comprise the previously mentioned planet gear 25. The planet gears are mounted by bearings as shown in individual stub shafts 64. The planet gear carrier 22 has an eccentric outer peripheral surface of cylindrical cross section on which the previously mentioned ring gear 24 is mounted by bearings 64, the ring gear being of the configuration of an axially elongated cylinder. Thus the ring gear 24 rotates on an axis that is offset from the common axis of the axis of rotation of the sun gear 20 and the carrier 22.

The cylindrical body of the cargo-propelling roller 32 fixedly embraces the elongated ring gear and at its opposite ends carries internal rings and 66 which are secured thereto by suitable screws 67 and which retain corresponding O-rings 68 in peripheral contact with the carrier 22.

For the purpose of frictionally coupling the ring gear 24 and the carrier 22, a collar 70 mounted on the carrier and secured thereto by a radial screw 72 cooperates with a circumferential wafer spring 74 of undulating configuration which is confined under light stress between the collar 70 and the previously mentioned internal ring 65 of the cargo-propelling roller 32. Thus the wafer spring is effective to lock up the planetary gear train in a yielding manner to cause orbital movement of the cargo propelling roller 32.

In the construction shown, the motor 50 and associated components for actuating the sun gear 20 are enclosed in a low profile housing 75 with the sun gear and the carrier extending beyond one end of the housing as shown in FIGS. 5 and 7. As best shown in FIG. 5, a unitary part of the housing 75 is a guard 76 that extends around the opposite sides and outer end of the cargo-propelling roller 32, the purpose of the guard being to protect the roller and especially so at the lower retracted position of the roller. The guard 76 also serves to support outer bearing 60 of the sun gear shaft 58.

As shown in FIGS. 6, 7 and 10, both the upper portion of the housing 75 and the upper portion of the guard 76 are of what may be termed a chamfered configuration having inclined marginal surfaces 78. These inclined marginal surface 78 serve to ward off or cam upwardly any sagging portion of a cargo unit that may tend to make impact against the housing or guard. FIG. 10 shows the range of translation of the cargopropelling roller 32 between a lower limit position 80 within the boundaries of the housing 75 and an upper limit position 82 at which the roller protrudes sufficiently above the housing to make effective traction contact with cargo items.

The means to operatively connect the motor shaft 52 to the spur gear 55 may comprise reduction gearing in the form of two stages of planetary gearing. In the first stage a sun gear 84 on the motor shaft 52 meshes with first stage planet gears 85 which are mounted on a first stage planet gear carrier 86. The planet gears 85 mesh with both the first stage sun gear 84 and a first stage ring gear 88. The first stage planet gear carrier 86 is fixedly mounted on a stub shaft 90 which carries a second stage sun gear 92. The second stage sun gear meshes with second stage planet gears 94 which in turn mesh with a second stage ring gear 95. The second stage planet gears 94 are mounted on a second stage planet gear carrier 96 which is keyed to a stub shaft 98 that is joumalled in bearings 100 and carries the previously mentioned first spur gear 55.

The two stages of planetary gearing reduces the peripheral speed of the cargo-shifting roller 32 to a suitable rate, which may be approximately sixty feet per minute.

The use of planetary gears for reduction gearing of advantageous in that it permits the combination with the reduction gearing to a torque limiter to protect the mechanism in the event that a cargo item under propulsion by the cargo roller 32 is blocked with consequent abrupt rise in stressing of the parts of the mechanism. For this purpose, the first stage ring gear 88 is mounted on bearings 103 and suitable friction means resists rotation of the ring gear.

In the present embodiment of the invention, as shown in FIGS. and 6, the frictional torque limiting means comprises a pair of arcuate friction shoes 104 which are interconnected by a fixed pivot 105 and are interconnected at their confronting outer ends by means including a screw 106 which provides for adjustment of the pressure with which the shoes grip the ring gear 88. The magnitude of the torque that is resisted by the friction shoes is above the normal torque output of the motor but is below the torque output augmented by inertia of the motor. When a cargo item being shifted by the roller 32 is suddenly obstructed, the consequent abrupt rise in torque resistance results first in dissipation of power by the friction shoes and then stalling of the motor.

It is to be understood, of course, that any suitable torque limiter may be used within the scope of the invention. For example, with the first stage ring gear 88 permanently immobilized, the stub shaft 98 may be made in two sections 98a and 98b as shown in FIG. a and the two sections may be yieldingly interconnected by a conventional adjustable friction clutch 108.

The construction of the previously mentioned yoke 40 that carries the previously mentioned first and second latches 36, 38 may be understood by referring to FIGS. 5, 6, 8 and 9. As shown in FIGS. 3 and 9 the yoke 40 has a full-length side plate 110 and two iongitudinally spaced shorter opposite side plates 112 and 114. The short side plate 1 12 is connected to the longer side plate 110 by a pair of studs 115 which carry corresponding anti-friction rollers 117 for cooperation with corresponding fixed upper and lower guide plates 118 shown in FIG. 6. A third stud 119 carries a roller 36 which is the previously mentioned first latch 36. The short side plate 114 is connected to the longer side plate by screws 120 that pass through spacer block 121 and by a pair of studs 122 that carry corresponding antifriction rollers 123. The previously mentioned second latch 38 is a projection of the spacer block 121 between the side plates 110 and 114. The yoke 20 slides on the four anti-friction rollers 117, 123 along the guideway that is formed by guide plates 118.

To cooperate with the first latch 36 and the second latch 38, the planet gear carrier 22 is fixedly embraced by a sleeve 125 (FIG. 7) with an integral collar 126 that is anchored to the carrier by a radial screw 128. The outer circumferential surface of the collar 126 is concentric to the axis of rotation of the carrier 22 and, as shown in phantom in FIG. 9, the collar is formed with the previously described latching recess 35 of the carri- As shown in FIG. 5, the mechanism for controlling the yoke 40 comprises the previously mentioned solenoid 44 which has an armature 130 slidingly mounted in a slide bearing 132. The armature 130 is connected by a pivot 134 to one arm of a bellcrank 135 that is rotatable about a fixed pivot 136. The second arm 138 of the bellcrank extends into a circular aperture 140 of the long side plate 110. As indicated in FIG. 8 the circular aperture 140 may be provided with a bushing 142. The second arm 138 of the bellcrapk 135 carries a roller 144 for rolling contact with the bushing 142 to control reciprocation of the yoke 40.

To bias the yoke 40 towards its normal limit position a coil spring 42 which is the previously mentioned spring 42 embraces the armature 130 under compression between the body of the solenoid 144 and a collar 145 that is fixedly mounted on the armature. Thus when the armature is deenergized, the spring 42 is expanded as shown in FIG. 5 to cause the bellcrank 35 to be urged clockwise to hold the yoke 40 in its normal position which is towards the bottom of FIG. 5. At this normal position of the yoke, the pressure of the spring 42 urges the second latch 38 into the latch seat 35 as previously described in reference to FIG. 2. On the other hand, when the solenoid is energized, the second latch 38 is retracted and the first latch 35 is advanced towards the collar 126 of the planet gear carrier as heretofore described. It is apparent that the two latches are effective for carrying out the operating cycle regardless of the direction in which the carrier 22 is rotated.

A suitable control circuit for a cargo-shifting unit of the described construction is shown in FIG. 12 wherein a switch 146 operated by a push button 147 closes a a direct current circuit 148 to energize the previously mentioned solenoid 44 which, as previously described, mechanically operates the previously described switch 46, and the switch 46 in turn controls a relay 152 for energization of the motor 50. The switch 146 energizes the solenoid 44 as long as the push button 147 is depressed and incorporates a time delay to keep the solenoid energized for a few seconds after the push button is released. Thus the push button may be momentarily depressedto cause a cargo item to be propelled a few feet. The four leads 154 that terminate at the motor are connected to a reversing relay 155. A toggle switch 156 which may be shifted in opposite directions causes opposite rotations of the motor 50. The push button switch 146 and the toggle switch 156 for the reversing switch are mounted on the same control panel. FIG. 11 shows such a control panel 158 that is pendant on a control cable 159 and further shows a similar fixed control panel 160. The pendant control panel 158 may be moved into and out of the cargo space and may be hung on the wall in the cargo space when not in use.

FIG. 11 shows diagrammatically how the cargo space of an aircraft may be provided with structure of the character disclosed in the Davidson patent, the structure including a set of ball mats 162 in the area opposite the side door opening 164 of the aircraft and further including longitudinal roller trays 165 to move cargo from the ball mats to the front bay of the cargo space and additional roller trays 166 to facilitate movement of cargo forwardly from the ball mat area.

By way of example of how the present invention may be applied to the structure shown in FIG. 12, a first pair of coaxial powered cargo-propelling rollers 32a are positioned near the doorway 164 to cooperate with the ball elements 168 of the ball mat area to advance cargo items from the doorway into the central portion of the ball mat area. The ball mat area further includes two power actuated cargo-propelling rollers 32b with their axis perpendicular to the axis of the aircraft to cooperate with the ball elements 168 to shift cargo items either forward to the roller trays 165 or rearward to the roller trays 166. The forward bay which is provided with the roller trays 165 has a power-actuated cargo-propelling roller 32c to complete the transfer of cargo items from the ball mat area to the bay.

The rearwardly extending portion of the cargo area is provided with a succession of spaced cargo-propelling rollers 32d, 32e, 32f, etc. to cooperate with the roller trays 166, the successive cargo-propelling rollers being effective in sequence to shift cargo items as far rearward as required. The rectangle 170 with diagonals represents a cargo item stowed in the forward bay and the similar rectangle 171 represents a cargo item in route to the rear end of the cargo space. The control panel 160 that is mounted at a suitable location adjacent the doorway 164 may have two switches, namely a reversing switch to determine the direction of rotation of all of the various cargo-propelling rollers, a push button to control energization of the cargo-propelling rollers 32b and 320. The pendant panel 158 may also have two switches, namely, a switch to energize the cargo-propelling roller 32a and a switch to energize the cargo-propelling roller 32b, roller 32b being controlled by either panel. After a foot switch 132d has been operated to energize roller 32 d to advance a cargo item rearwardly of the aircraft to the limit of the range of cargo-propelling roller 32d, the operator may walk into the cargo space and depress a foot switch 172e to energize the cargo-propelling roller 32c. In like manner a foot switch 172f controls the cargo-propelling roller 32f and a foot switch 172g controls the next cargo shifting roller (not shown) etc. It is to be noted that the foot switches are safely remote from the cargo-propelling rollers that they control. The described procedure is safe because the operator is always to the rear of any cargo item that is moving under power.

Other Applications of the Invention By way of example of another use for the underlying concept of the invention, FIG. 13 shows a grinding wheel 175 which may be incrementally advanced towards a workpiece 176 that is reciprocated as indicated by the double arrow 178. The mechanism for driving the grinding wheel on its axis and for shifting the grinding wheel incrementally towards the workpiece 176 comprises the previously described eccentric planetary gear train which includes a planet gear carrier 22a. The planet gear carrier 22a is in the form of a worm gear that is controlled by a worm 180 on a control shaft 182. The outer end of the control shaft has a disk 184 provided with a crank 185 for manual rotation of the control shaft. Suitable means to indicate precisely the degree to which the grinding wheel is advanced towards the workpiece 76 may be in the form of a circular scale 186 on the disk 184 and an index pointer 188 that overhangs the circular scale. It is apparent that the operator in advancing the grinding wheel 175 towards the workpiece by means of crank 185 may observe the scale 186 and the index pointer 188 to control the advance of the grinding wheel with high precision.

My description in specific detail of the selected embodiments of the invention will suggest to those skilled in the art various changes, substitutions and other departures from my disclosure within the scope of the invention.

I claim:

1. A combination of a rotary body and a mechanism to rotate the rotary body on its axis and to move the rotary body laterally of its axis, comprising:

a power-actuated sun gear;

a planet gear carrier;

a ring gear unitary with the rotary body and concentric therewith, the ring gear being rotatably mounted on the planet gear carrier eccentrically thereof whereby rotation of the carrier moves the rotary body along an orbital path;

a planet gear carried by the planet gear carrier in mesh both with the sun gear and the ring gear; and

means to rotate the planet gear carrier to move the rotary body along the orbital path.

2. A combination as set forth in claim 1 which includes means to releasably immobilize the carrier to maintain the rotary body at a given position on the orbital path.

3. A combination as set forth in claim 1 which further includes means to cause power flow from the sun gear to the carrier to rotate the carrier to move the rotary body along the orbital path.

4. A combination as set forth in claim 3 in which the further means to cause power flow to the carrier comprises means to hold the ring gear against rotation about its axis while permitting the ring gear to move along the orbital path.

5. A combination as set forth in claim 3 in which the planet gear carrier has a latch shoulder thereon for cooperation with a latch at an advanced position of the rotary body on said orbital path;

a latch normally biased away from the planet gear carrier;

and which includes means to overcome the bias of the latch whenever the sun gear is energized,

whereby starting with the rotary body at a position retracted from said advanced position, energization of the sun gear initially causes the planet gear carrier to rotate until said shoulder is available to the latch, whereupon the latch engages the shoulder to immobilize the planet gear carrier,

and whereby termination of energization of the sun gear results in release of the latch to permit the planet gear carrier to rotate to retract the roller.

6. A combination as set forth in claim 5 which includes a second latch to immobilize the planet gear carrier at the retracted position of the rotary body;

in which the second latch is biased for normal engagement with the planet gear carrier;

and which includes means to overcome the bias of the second latch and to actuate the sun gear in response to a control signal.

7. A combination as set forth in claim 6 wherein said means to rotate the carrier includes a motor to actuate the sun gear;

and which includes a switch to energize the motor, said switch being responsive to the position of said second latch to cause the motor to be energized only when the second latch is out of engagement with the planet gear carrier.

8. A combination as set forth in claim 7 which includes a solenoid to actuate the second latch;

which includes a control switch with a push button to energize the solenoid as long as the push button is depressed;

and which includes time delay means to prolong the energization of the solenoid for a predetermined number of seconds after the push button is released.

9. A combination as set forth in claim 6 in which the two latches are mounted on a latch yoke;

which includes spring means to urge the latch yoke in one direction to urge the first latch out of engagement with the carrier and to urge the second latch into engagement with the carrier;

and which includes solenoid means responsive to the control signal to urge the yoke in the opposite direction in opposition to said spring means to urge the second latch out of engagement with the carrier and to urge the first latch into engagement with the carrier.

10. A combination as set forth in claim 9 wherein said means to rotate the carrier includes a motor to actuate the sun gear and which includes a switch to energize the motor,

said switch being responsive to the position of the latch yoke to energize the motor only when the latch yoke is in a position with said second latch out of engagement with the planet gear carrier.

11. A combination as set forth in claim 6 in which the latch shoulder in the planet gear carrier is in an outer circumferential portion of the planet gear carrier for alternate engagement by the two latches.

12. A combination as set forth in claim 1 in which said sun gear, carrier, ring gear and planet gear constitute a planetary gear train;

and in which the means to rotate the carrier comprise releasable means to lock up the planetary gear train to cause the planetary gear train to rotate as a unit about the axis of the sun gear to move the rotary body along the orbital path.

13. A combination as set forth in claim 1 in which means to rotate the carrier comprises means to couple the ring gear and carrier to cause rotation of the carrier to move the rotary body along the orbital path.

14. A combination as set forth in claim 13 in which said coupling means comprises means to frictionally couple the ring gear and carrier.

15. A combination as set forth in claim 1 wherein said means to rotate the carrier includes a prime mover to actuate the sun gear and means to limit the torque transmitted to the sun gear by the prime mover.

16. A combination as set forth in claim 15 which includes reduction gearing to transmit power from said prime mover to the sun gear; and

in which said torque limiting means is combined with the reduction gearing.

17. A combination as set forth in claim 16 in which said reduction gearing includes planetary gearing having an input component operatively connected to the prime mover, an output component operatively connected to the sun gear and a reaction component;

and in which said torque limiter means comprises friction means to oppose rotation of the reaction component.

18. A combination as set forth in claim 15 in which the rime mover is a motorw rch includes a normally open circuit to energize the motor;

and in which solenoid means overcomes the bias of both latches in response to closing of the motor circuit.

19. A combination as set forth in claim 18 in which said motor is reversible;

which includes remote switch means to control energization of the motor;

and which includes a remote reversing switch to control the direction of rotation of the motor thereby to control the direction of rotation of the roller. 

1. A combination of a rotary body and a mechanism to rotate the rotary body on its axis and to move the rotary body laterally of its axis, comprising: a power-actuated sun gear; a planet gear carrier; a ring gear unitary with the rotary body and concentric therewith, the ring gear being rotatably mounted on the planet gear carrier eccentrically thereof whereby rotation of the carrier moves the rotary body along an orbital path; a planet gear carried by the planet gear carrier in mesh both with the sun gear and the ring gear; and means to rotate the planet gear carrier to move the rotary body along the orbital path.
 2. A combination as set forth in claim 1 which includes means to releasably immobilize the carrier to maintain the rotary body at a given position on the orbital path.
 3. A combination as set forth in claim 1 which further includes means to cause power flow from the sun gear to the carrier to rotate the carrier to move the rotary body along the orbital path.
 4. A combination as set forth in claim 3 in which the further means to cause power flow to the carrier comprises means to hold the ring gear against rotation about its axis while permitting the ring gear to move along the orbital path.
 5. A combination as set forth in claim 3 in which the planet gear carrier has a latch shoulder thereon for cooperation with a latch at an advanced position of the rotary body on said orbital path; a latch normally biased away from the planet gear carrier; and which includes means to overcome the bias of the latch whenever the sun gear is energized, whereby starting with the rotary body at a position retracted from said advanced pOsition, energization of the sun gear initially causes the planet gear carrier to rotate until said shoulder is available to the latch, whereupon the latch engages the shoulder to immobilize the planet gear carrier, and whereby termination of energization of the sun gear results in release of the latch to permit the planet gear carrier to rotate to retract the roller.
 6. A combination as set forth in claim 5 which includes a second latch to immobilize the planet gear carrier at the retracted position of the rotary body; in which the second latch is biased for normal engagement with the planet gear carrier; and which includes means to overcome the bias of the second latch and to actuate the sun gear in response to a control signal.
 7. A combination as set forth in claim 6 wherein said means to rotate the carrier includes a motor to actuate the sun gear; and which includes a switch to energize the motor, said switch being responsive to the position of said second latch to cause the motor to be energized only when the second latch is out of engagement with the planet gear carrier.
 8. A combination as set forth in claim 7 which includes a solenoid to actuate the second latch; which includes a control switch with a push button to energize the solenoid as long as the push button is depressed; and which includes time delay means to prolong the energization of the solenoid for a predetermined number of seconds after the push button is released.
 9. A combination as set forth in claim 6 in which the two latches are mounted on a latch yoke; which includes spring means to urge the latch yoke in one direction to urge the first latch out of engagement with the carrier and to urge the second latch into engagement with the carrier; and which includes solenoid means responsive to the control signal to urge the yoke in the opposite direction in opposition to said spring means to urge the second latch out of engagement with the carrier and to urge the first latch into engagement with the carrier.
 10. A combination as set forth in claim 9 wherein said means to rotate the carrier includes a motor to actuate the sun gear and which includes a switch to energize the motor, said switch being responsive to the position of the latch yoke to energize the motor only when the latch yoke is in a position with said second latch out of engagement with the planet gear carrier.
 11. A combination as set forth in claim 6 in which the latch shoulder in the planet gear carrier is in an outer circumferential portion of the planet gear carrier for alternate engagement by the two latches.
 12. A combination as set forth in claim 1 in which said sun gear, carrier, ring gear and planet gear constitute a planetary gear train; and in which the means to rotate the carrier comprise releasable means to lock up the planetary gear train to cause the planetary gear train to rotate as a unit about the axis of the sun gear to move the rotary body along the orbital path.
 13. A combination as set forth in claim 1 in which means to rotate the carrier comprises means to couple the ring gear and carrier to cause rotation of the carrier to move the rotary body along the orbital path.
 14. A combination as set forth in claim 13 in which said coupling means comprises means to frictionally couple the ring gear and carrier.
 15. A combination as set forth in claim 1 wherein said means to rotate the carrier includes a prime mover to actuate the sun gear and means to limit the torque transmitted to the sun gear by the prime mover.
 16. A combination as set forth in claim 15 which includes reduction gearing to transmit power from said prime mover to the sun gear; and in which said torque limiting means is combined with the reduction gearing.
 17. A combination as set forth in claim 16 in which said reduction gearing includes planetary gearing having an input component operatively connected to the prime mover, an output component operatively cOnnected to the sun gear and a reaction component; and in which said torque limiter means comprises friction means to oppose rotation of the reaction component.
 18. A combination as set forth in claim 15 in which the prime mover is a motor; which includes a normally open circuit to energize the motor; and in which solenoid means overcomes the bias of both latches in response to closing of the motor circuit.
 19. A combination as set forth in claim 18 in which said motor is reversible; which includes remote switch means to control energization of the motor; and which includes a remote reversing switch to control the direction of rotation of the motor thereby to control the direction of rotation of the roller. 